Abstract Text: Blood cell analysis is a major pillar of biomedical research and healthcare. As these analyses are performed in central laboratories, a rapid shipment from collection site is needed because cells and biomarkers may degrade rapidly. Dried blood spots allow the preservation of nucleic acid, protein or metabolite molecules, but entire cells have never been recovered for downstream analysis. Herein, we demonstrate that leucocyte drying, preservation and subsequent elution from a specific polyester membrane is compatible with flow cytometry analysis and sorting. While red blood cells are lysed upon drying, most leucocytes are permeabilized upon the considered drying process, which allowed for an easy staining of all cellular compartments. Providing recovery above 50%, elution from the polyester membrane of previously dried leucocytes could be performed by its simple but yet vigorous shaking while immersed in buffer. As leucocytes eluted from dried blood spots were initially found to have an altered structure upon analysis, it could be improved by adding fixative in the elution buffer. While ongoing studies are performed, more than 100 common immunophenotyping markers were already tested and found to be compatible with the proposed approach. Specimen stability for more than three months as well as RNAseq after sorting have also been demonstrated. Leucocytes from blood can thus be dried, shipped and/or stored for up to several months, then recovered for a wide variety of analyses. We believe this approach may facilitate not only biomedical applications worldwide, but also multicentric clinical research studies which often face implementation challenges.
